v5.1.0

Added

• @tool accepts a sync body. Only @workflow still requires async def, because every
  orchestration primitive on WorkflowCtx is awaited and a sync body cannot reach one. A tool has
  nothing to await, and both paths that play one now put a sync body on a worker thread: the
  model-facing path already did, and ctx.invoke() does now. The refusal previously applied to
  both kinds, so the richer form was also the more restrictive one.
• Content blocks and Observer import from the package root. ImageBlock, TextBlock,
  ContentBlock, ResourceBlock, AudioBlock, DataBlock and Observer are exported from
  agentdeck alongside Agent and Deck, rather than only from agentdeck.core.content and
  agentdeck.core.ports. Sending an agent an image and watching a deck's events are both
  first-contact tasks, and both previously required knowing an internal path to reach a public
  capability.

Removed

• A plain function carrying a ToolCtx[...]/WorkflowCtx[...] parameter in tools= is
  refused. Only @tool may declare one now; build() names the callable and shows the
  decorator to add. instructions= and hooks= callables are unaffected, and a context-free
  plain function still compiles exactly as before.

Changed

• A durable event log now says what it does not make durable. Setting AGENTDECK_EVENTS to
  anything other than memory:// while AGENTDECK_SESSION is unset logs a warning: the log
  survives a restart, the conversation the model sees does not. The old warning fired only for
  memory://, so configuring a durable log silenced the one message and left the reader believing
  recall was handled.
• Sending an agent an image is documented where agents are. build-your-deck/agents gains a
  section on content blocks, and build-your-deck/tools states that a tool cannot carry an image:
  tool results are text, so a returned data: URI reaches the model as a string.
• The error taxonomy moved to agentdeck/core/errors.py. agentdeck.errors re-exports the
  same class objects, so every from agentdeck.errors import ... and except ConfigError is
  unchanged. What changes is what a traceback prints: agentdeck.core.errors.ConfigError,
  not agentdeck.errors.ConfigError. Core raises these now, which is where CLAUDE.md §2
  already placed the taxonomy.

Fixed

• Deck.build() no longer rejects a model for a missing provider env var. The credential
  check only ever recognized anthropic/gemini/ollama/openrouter and otherwise demanded
  OPENAI_API_KEY/OPENAI_BASE_URL, so a litellm/... or any-llm/... model authenticated
  through its own provider's own convention (Vertex ADC, an IAM role, ...) failed to build over a
  credential it would never use. Model authentication belongs to the wrapped Agents SDK and the
  selected provider, not Deck.build(); a real auth failure now surfaces at the actual call,
  as the provider's own error.
• ctx.reporter now works from a sync @tool body. It previously did nothing: Reporter.info
  and friends are async def, and a worker thread has no event loop to await one on, so a bare
  call built an unawaited coroutine and quietly reported nothing. ctx.reporter from a sync body
  is now a sync-callable facade that marshals the report onto the run's own loop and blocks until
  it lands, preserving order against the tool's own return. ctx.safepoint() from a sync body now
  raises ConfigError naming the constraint, instead of the same silent no-op.
• A sync @tool body now runs on a bounded, deck-owned worker pool, not the interpreter-global
  default asyncio.to_thread() executor. A Run cancelled while its sync body is still on a
  worker now ends CANCELLED, never flipped back to COMPLETED by the body's eventual,
  uninterruptible return; a queued-but-not-started call is cancelled outright and its body never
  runs. The pool drains on Deck.aclose() along with everything else this Deck owns.
• @function_tool over a ToolCtx parameter now says what to do about it. The Agents SDK
  decorator builds its argument schema from every parameter it does not recognise, so a context
  one used to fail at decoration with PydanticSchemaGenerationError: Unable to generate pydantic-core schema for <class 'agentdeck.core.control.Gate'>, naming a private type and no
  fix. It now raises ConfigError naming the fix: use agentdeck's own @tool.